const fp = require('lodash/fp')

// 数据
// horsepower 马力，dollar_value 价格，in_stock 库存
const cars = [
	{ name: 'Ferrari FF', horsepower: 660, dollar_value: 700000, in_stock: true },
	{ name: 'Spyker C12 Zagato', horsepower: 650, dollar_value: 648000, in_stock: false },
	{ name: 'Jaguar XKR-S', horsepower: 550, dollar_value: 132000, in_stock: false },
	{ name: 'Audi R8', horsepower: 525, dollar_value: 114200, in_stock: false },
	{ name: 'Aston Martin One-77', horsepower: 750, dollar_value: 1850000, in_stock: true },
	{ name: 'Pagani Huayra', horsepower: 700, dollar_value: 1300000, in_stock: false }
]

// 练习1 - 方法改写
// let isLastInStock = function (cars) {
// 	// 获取最后一条数据
// 	let last_car = fp.last(cars)
// 	// 获取最后一条数据的 in_stock 属性值
// 	return fp.prop('in_stock', last_car)
// }
// console.log(isLastInStock(cars))

const f1 = fp.flowRight(fp.prop('in_stock'), fp.last)
// const f1 = fp.compose(fp.prop('in_stock'), fp.last)
console.log(f1(cars))

// 练习2
const f2 = fp.flowRight(fp.prop('name'), fp.first)
console.log(f2(cars))

// 练习3 － 函数组合
let _average = function (xs) {
	return fp.reduce(fp.add, 0, xs) / xs.length
}
// let averageDollarValue = function (cars) {
// 	let dollar_values = fp.map(function(car){
// 		return car.dollar_value
// 	}, cars)
// 	return _average(dollar_values)
// }
// console.log(averageDollarValue(cars))
// let compose = fp.flowRight(_average, fp.map(fp.prop('dollar_value')))
let compose = fp.compose(_average, fp.map(fp.prop('dollar_value')))
console.log(compose(cars))

// 练习4
let _underscore = fp.replace(/\W+/g, '_')
let sanitizeNames = fp.flowRight(_underscore, fp.toLower) 
console.log(sanitizeNames("Hello World"))